Trimmer mechanism for sewing machines



vSept 27,1936. r F. M. CARD 7 1 2,055,424

TRIMMER MECHANISM FOR SEWING MACHINES 7 [Filed May 25, 1935 2 Sheets-Sheet 1 r VINVENTORF Frederie M Canl "W ATTORNEY Sept. 22, 1936. M RD 2,055,424

TRIMMER MECHANISM FOR SEWING MACHINES I Filed May 25 1935 2 Sheets-Sheet 2 gwomtoz Patented Sept. 22, 1936 UNITED sT'ATjEs PATENT OFFICE Frederic MQCard, Bridgeport, 001111., assignor to --The Singer -Manufacturing Company, Elizaboth, N. J., a corporation of New Jersey ApplicationhlWay: 25; 1935, Serial No. 23.35?

4Claims. (or. 112-125) This invention relates to improvements in work-severing devices for sewing machines and is particularly adapted for use in connection with hemstitching machines for severing the cross- 5 bars of a hemstitch seam in the production of picot-edging.

The primary object of the present invention is to provide a work-severing device of simple con struction and arrangement whereby a movable i cutting knife may be conveniently rendered in efiective. v l 1 I h With the above and other objects in view, the

invention consists in the work-severing device hereinafter described in connection 'with the accompanying drawings which illustrate apreferred embodiment of the invention."

In the drawings, Fig. 1 is a front end elevation of the bracket-arm head of a hemstitchi ng ma- .chine containing the improved work-severing de- 20 'vice,the left presser-foot beingpartly broken away and the work-support being shown in section. Fig. 2 is a rear side elevation, partly in section, of a portion of the machine. Fig. 3is a top plan view, partly in section, illustrating the severing 25 device in its operative relation to the presser-foot of the machine. Fig. 4 represents, in perspective, the component parts'of thecuttingknife and its carrier in disassembledrelationship. Fig. 5 is: a detail sectional view, on a large scale, of the 30 knife-holder securing means.

Referring to the drawings, the present invention is illustrated as embodied in a two-needle hemstitching machine constructed substantially as disclosed in the U. S. patent to G. M. Eames 5 et al., No. 1,721,072, July 16, 1929. In general, this hemstitching machine has a work-support including a bed-plate I and a throat-plate 2 provided with a front-piercer aperture 3, a combination needle-and-piercer slot 4, and a knife- .40 clearance slot 5 rearwardly of the slot 4. The work is advanced by a feed-dog 6 having spaced sections operating through suitable slots provided in the throat-plate at opposite sides of the slots 4 and 5.

45 Overhanging the cloth-plate I is a bracket-arm l terminating in a head 8. Rotatably journaled in said bracket-arm is a horizontally disposed actuating shaft 9 operatively connected to vertically reciprocate a needle-bar H) in suitable bear- 50 ings provided in the head 8. Fulcrumed upon a bracket l I carried by the lower end of the needlebar It] are laterally spaced needle-holders I2, each carrying a needle l3. Secured to said needle-holders l2 are guide-rods l4 to which 55 vibratory movements are imparted by operative connections with endwise reciprocatory pitmen l5, disposed at the rear side of the bracket-arm as more fully disclosed in said prior Patent No. 1,721,072. A front piercer I6 is illustrated as carried by the needle-bar bracket II in position to enter the throat-plate aperture 3. The stitchforming mechanism includes suitable loop-takers (not shown) which cooperate with the needles. [3 below the throat-plate.

The bracket-arm head 8 is provided with suita- 1 ble bearings forthe usual, vertically movable presser-bar ll carrying presser-feet l8 which are opposed to the work-engaging sections of the feed-dog 6. The work-engaging portions of said presser-feet 18 are laterally spaced from each 15 other to expose therebetween the throat-plate slots 4 and 5, and the front pierceraperture 3.

Also vertically movable in suitable bearings provided in the bracket-arm head 8 is a piercerbar 9,300 the lower end of which is secured .a 20 holder 20 for a piercer 2|. Secured .upon the piercer-bar I9 is a collar 22 to which is operatively connected a crank-arm 23 carried by a horizontally disposed rock-shaft 24 journaled in bearing lugs 25 and 26 at the rear side of the bracket- 25 arm I. 'The rock-shaft 24 carries another crankarm 21 pivotally connected to one end of a pitman 28, of which the opposite end is provided with a strap embracing'an'eccentric 29 carried by the needle-reciprocating shaft 9. The piercer 2lfis-130 thus reciprocated vertically and serves to shape the work-apertures which separate the cross-bars of the usual hemstitch seam.

The present invention resides more particularly in an improved work-severing device. Secured by screws, 38 upon the front end of the head 8 is a primary bracket 3| from which depends a supporting bar 32. Clamped upon the bar 32, for vertical adjustment, is a split boss 33 of an auxiliary bracket 34 having its rear- Ward face recessed to provide a seat for a horizontally disposed member 35 of an angular supporting arm 35, 36. The arm-member 35 is secured by screws 31 to the bracket 34 for adjustment crosswise of the line of seam formation. The member 36 of the supporting arm depends from the bracket 34 and terminates at its lower end in a horizontally apertured bearing-boss 38 close to but spaced from the work-support sufficiently to provide work clearance.

J ournaled in the bearing-boss 38 is a fulcrumpin 39 extending laterally from a vertically vibratory lever 40 provided in a side face thereof and lengthwise of said lever with an arcuate guideway 4|. The lever 40 extends rearwardly from its fulcrum-axis and at its rearward end has an apertured ear 42 pivotally connected to the lower end of a link 43, of which the upper end is pivotally connected to a crank-arm 44 suitably secured upon the piercer-actuating rockshaft 24. The guideway 4| preferably has its longitudinal center line passing. vertically above the fu1c11umeaxis'39 of the lever 40. v 3

Shiftable lengthwise of the lever 40, in the guideway 4| thereof is a knife-carrier 45 having an aperture 46 receiving the shank of a threaded bolt 41 which passes throughian arciiate's'lot iil extending lengthwise of the side wall of the lever guideway 4|. The slabbed head of the bolt 41 is slidingly disposed in the lever slot 48. 'Ifhreaded upon the bolt 41 is a nut 50 Whichis recessed at its inner end to house a coil-springjj embracing the shank of said bolt. The "spring'5l serves to retain the knife-carrier 45 in the. leverthereby prqv dm for conveniently shifting the knife-carrier 45 in said guideway 4|.

- The knife-carrier 45 has a splitforward end 'toreceive the shank of a knife 52 having a verticallydi spo'se dand substantially straight cuttirig edge 53; theknife-shank being detachably securedito its carrier by means of screws 54. In its forward or operative'position,the'knife 52 depends into the slot of thethroat-plate 2, the cutting edge 53 of said knife being opposed to the direction of} feed'ofthe work and being vibrated -in substantially the vertical plane containing the center line of'the hemstitch seam as it is formed. v

It will bereadily understood that as the work is advanced by the ,feeding'mechanism of the machine "pastjthe stitch-forming mechanism thereof," the cross-bars, of the hemstitch seam "are br ought'int engagement with and are severed by the vibrating knife 52rearwardly of the point of'seam-fformation. The knife 52 may be shifted "intoj a'n ineffective position by sliding the'knifeca'rri er i45'in vertical plane of the knife edge 53 and ina direction rearwardly in thefleverguideway M, relatively. to the fulcrum 'axis 39 of said lever. The curvature of the guideway 4| isiS i-ch that'when the carrier 45 is shifted rear- *wardly' 'thereof, the knife 52 is correspondingly fmoijd reajrwardly and also upw ardly out of the throat-plate slot 5; so that in its ineffective p0- sition the lower portion of the knife-edge 53 is located above the lower face of the bearing boss 38 of the supporting-arm 36 and closely adjacent to the fulcrum-axis 39 of the lever. The knife 52 is therefore shiftable into an ineffective position wherein the knife-edge 53 is protected against being caught bythe work. The nut 50' provides convenient manually engageable means for shifting the knife-carrier 45 in its guideway 4|.

' Having thus set forth the nature of the invention, lwhat 'Icl'aim herein is:

1. A trimmer mechanism for sewing machines comprising, anactuating lever vibratory about a fnlcrnm axis and provided with an arcuate guideway 'a work-severing knife, and a knifecarrier slidablymounted in said guideway providing-forshifting'movement of said knife out of and into operative positions thereof.

2. In a sewing machine, a, work-support including a throat plate having a needle-aperture, ingfandwork-fee ding mechanism, a

eringknife'ha'ving its cutting edge disse e rwara1y of the throat-plate needleaperture-ina' vertical plane through said needleaperture, a vibratory actuating lever provided *with a' guidway extending'lengthwise of said eve -a carrierfor "said knife shiftably disposed in said guideway, and means for vibrating said lever. i

3. In a sewing machine, a horizontally disposed we'rk-"support, stitch-forming mechanism, work-feeding mechanism, a-supporting bracket, a lever fulcruined uporfsaid bracket for vibratory movement about a horizontal-axis transverse to the direction N of feed-of" the work, an arcuate guideway extending'flengthwise of said lever, a knifekarrierfshiftably secured in said guideway, andme ansifor vibrating said lever.

A trimmerfme'chanismfor sewing-machines cqmprisinggavibratory lever provided with a guidewayfand with a slot extending longitudinally oi said guideway, a knife-carrier slidably dis- *aper re" in aliriment with said slot, abolt exten ing through-sai'dslot and aperture, a knifea spring hoiisedbysaid nut in yielding engage- 'ment with said knife-carrier.

er isecuring nutthreaded upon said bolt, and

'FREDERIC M; CARD. 

